The use of filamentous hemagglutinin adhesin to detect immune responses toinfections in layer hens.

Abstract

is the aetiological agent of Spotty Liver Disease (SLD). SLD can cause significant production loss and mortalities among layer hens at and around peak of lay. We previously developed an enzyme linked immunosorbent assay (ELISA), SLD-ELISA1, to detectspecific antibodies from bird sera usingtotal proteins and sera pre-absorbed withproteins. The high specificity achieved with SLD-ELISA1 indicated the presence ofspecific antibodies in sera of infected birds. However, some of the reagents used in SLD-ELISA1 are time consuming to prepare and difficult to quality control. This understanding led to the search forspecific immunogenic proteins that could be used in recombinant forms as antibody capture antigens in immunoassay design. In this study, an immunoproteomic approach that combined bioinformatics analysis, western blotting, and LC MS/MS protein profiling was used, and a fragment of filamentous hemagglutinin adhesin (FHA), FHAwithspecific antigenicity was identified. Recombinant FHAwas used as antigen coating on ELISA plates to capture FHAspecific antibodies in sera of infected birds. SLD-ELISA2, based on the purified recombinant FHA fragment, is more user-friendly and standardizable than SLD-ELISA1 for screening antibody responses toexposure in hens. This study is the first report of the use of FHA from aspecies in immunoassays, and it also opens future research directions to investigate the role of FHA inpathogenesis and its effectiveness as a vaccine candidate.